Showing papers by "Temple University published in 1998"

Using the correct statistical test for the equality of regression coefficients

Abstract: Criminologists are often interested in examining interactive effects within a regression context. For example, “holding other relevant factors constant, is the effect of delinquent peers on one's own delinquent conduct the same for males and females?” or “is the effect of a given treatment program comparable between first-time and repeat offenders?” A frequent strategy in examining such interactive effects is to test for the difference between two regression coefficients across independent samples. That is, does b1= b2? Traditionally, criminologists have employed a t or z test for the difference between slopes in making these coefficient comparisons. While there is considerable consensus as to the appropriateness of this strategy, there has been some confusion in the criminological literature as to the correct estimator of the standard error of the difference, the standard deviation of the sampling distribution of coefficient differences, in the t or z formula. Criminologists have employed two different estimators of this standard deviation in their empirical work. In this note, we point out that one of these estimators is correct while the other is incorrect. The incorrect estimator biases one's hypothesis test in favor of rejecting the null hypothesis that b1= b2. Unfortunately, the use of this incorrect estimator of the standard error of the difference has been fairly widespread in criminology. We provide the formula for the correct statistical test and illustrate with two examples from the literature how the biased estimator can lead to incorrect conclusions.

Knowledge Management Processes and International Joint Ventures

Abstract: The management and processing of organizational knowledge are increasingly being viewed as critical to organizational success. By exploring how firms access and exploit alliance-based knowledge, the authors provide evidence to support the argument that the firm is a dynamic system of processes involving different types of knowledge. Using data from a longitudinal study of North American-based joint ventures (JVs) between North American and Japanese firms, they address three related research questions: (1) what processes do JV partners use to gain access to alliance knowledge; (2) what types of knowledge are associated with the different processes and how should that knowledge be classified; and (3) what is the relationship between organizational levels, knowledge types, and the transfer of knowledge? Although many generalizations have been drawn about the merits of knowledge-based resources and the creation of knowledge, few efforts have been made to establish systematically how firms acquire and manage new knowledge. Moreover, prior alliance research has not addressed in detail the nature of alliance knowledge and how knowledge is managed in the alliance context. The authors examine the processes used by alliance partners to transfer knowledge from an alliance context to a partner context. They identify four key processes-technology sharing, alliance-parent interaction, personnel transfers, and strategic integration-that share a conceptual underpinning and represent a knowledge connection between parent and alliance. Each of the four processes is shown to provide an avenue for managers to gain exposure to knowledge and ideas outside their traditional organizational boundaries and to create a connection for individual managers to communicate their alliance experiences to others. Although all of the knowledge management processes are potentially effective, the different processes involve different types of knowledge and different organizational levels. The primary types of knowledge associated with each process are identified and then linked with the organizational level affected by the transfer process. From those linkages, several propositions about organizational knowledge transfer and management are developed. The results suggest that although a variety of knowledge management strategies can be viable, some strategies lead to more effective knowledge transfer than others.

The Asymmetric Impact of Negative and Positive Attribute-Level Performance on Overall Satisfaction and Repurchase Intentions:

Abstract: The relationship between attribute-level performance, overall satisfaction, and repurchase intentions is of critical importance to managers and generally has been conceptualized as linear and symme...

Host–guest encapsulation of materials by assembled virus protein cages

Abstract: Self-assembled cage structures of nanometre dimensions can be used as constrained environments for the preparation of nanostructured materials1,2 and the encapsulation of guest molecules3, with potential applications in drug delivery4 and catalysis5. In synthetic systems the number of subunits contributing to cage structures is typically rather small3,6. But the protein coats of viruses (virions) commonly comprise hundreds of subunits that self-assemble into a cage for transporting viral nucleic acids. Many virions, moreover, can undergo reversible structural changes that open or close gated pores to allow switchable access to their interior7. Here we show that such a virion — that of the cowpea chlorotic mottle virus — can be used as a host for the synthesis of materials. We report the mineralization of two polyoxometalate species (paratungstate and decavanadate) and the encapsulation of an anionic polymer inside this virion, controlled by pH-dependent gating of the virion's pores. The diversity in size and shape of such virus particles make this a versatile strategy for materials synthesis and molecular entrapment.

A meta-analytic examination of assumed properties of child sexual abuse using college samples

Abstract: Many lay persons and professionals believe that child sexual abuse (CSA) causes intense harm, regardless of gender, pervasively in the general population. The authors examined this belief by reviewing 59 studies based on college samples. Meta-analyses revealed that students with CSA were, on average, slightly less well adjusted than controls. However, this poorer adjustment could not be attributed to CSA because family environment (FE) was consistently confounded with CSA, FE explained considerably more adjustment variance than CSA, and CSA-adjustment relations generally became nonsignificant when studies controlled for FE. Self-reported reactions to and effects from CSA indicated that negative effects were neither pervasive nor typically intense, and that men reacted much less negatively than women. The college data were completely consistent with data from national samples. Basic beliefs about CSA in the general population were not supported.

Effects of inhaled nitric oxide in patients with acute respiratory distress syndrome: results of a randomized phase II trial. Inhaled Nitric Oxide in ARDS Study Group.

Abstract: Objectives To evaluate the safety and physiologic response of inhaled nitric oxide (NO) in patients with acute respiratory distress syndrome (ARDS). In addition, the effect of various doses of inhaled NO on clinical outcome parameters was assessed. Design Prospective, multicenter, randomized, double-blind, placebo-controlled study. Setting Intensive care units of 30 academic, teaching, and community hospitals in the United States. Patients Patients with ARDS, as defined by the American-European Consensus Conference, were enrolled into the study if the onset of disease was within 72 hrs of randomization. Interventions Patients were randomized to receive placebo (nitrogen gas) or inhaled NO at concentrations of 1.25, 5, 20, 40, or 80 ppm. Measurements and main results Acute increases in PaO2, decreases in mean pulmonary arterial pressure, intensity of mechanical ventilation, and oxygenation index were examined. Clinical outcomes examined were the dose effects of inhaled NO on mortality, the number of days alive and off mechanical ventilation, and the number of days alive after meeting oxygenation criteria for extubation. A total of 177 patients were enrolled over a 14-month period. An acute response to treatment gas, defined as a PaO2 increase > or =20%, was seen in 60% of the patients receiving inhaled NO with no significant differences between dose groups. Twenty-four percent of placebo patients also had an acute response to treatment gas during the first 4 hrs. The initial increase in oxygenation translated into a reduction in the FIO2 over the first day and in the intensity of mechanical ventilation over the first 4 days of treatment, as measured by the oxygenation index. There were no differences among the pooled inhaled NO groups and placebo with respect to mortality rate, the number of days alive and off mechanical ventilation, or the number of days alive after meeting oxygenation criteria for extubation. However, patients receiving 5 ppm inhaled NO showed an improvement in these parameters. In this dose group, the percentage of patients alive and off mechanical ventilation at day 28 (a post hoc analysis) was higher (62% vs. 44%) than the placebo group. There was no apparent difference in the number or type of adverse events reported among those patients receiving inhaled NO compared with placebo. Four patients had methemoglobin concentrations >5%. The mean inspired nitrogen dioxide concentration in inhaled NO patients was 1.5 ppm. Conclusions From this placebo-controlled study, inhaled NO appears to be well tolerated in the population of ARDS patients studied. With mechanical ventilation held constant, inhaled NO is associated with a significant improvement in oxygenation compared with placebo over the first 4 hrs of treatment. An improvement in oxygenation index was observed over the first 4 days. Larger phase III studies are needed to ascertain if these acute physiologic improvements can lead to altered clinical outcome.

The death of distance: How the communications revolution will change our lives

Abstract: From the advent of electronic communications, there's been talk about how the world has been shrinking. Frances Cairncross, senior editor for the Economist, makes her case from an economical CiteULike is a free online bibliography manager. Register and you can start organising your references online. standpoint: The growing ease and speed of communication is creating a world where the miles have little to do with our ability to work or interact together. Cairncross predicts that it won't be long before people organize globally on the basis of language and three basic time shifts--one for the Americas, one for Europe, and one for East Asia and Australia. Much work that can be done on a computer can be done from anywhere. Workers can code software in one part of the world and pass it to a company hundreds of miles away that will assemble the code for marketing. And with workers able to earn a living from anywhere, countries may find themselves competing for citizens as people relocate for reasons ranging from lower taxes to nicer weather. Cairncross discusses about 30 major changes likely to result from these trends, including greater self-policing of businesses, an unavoidable loss of personal privacy, and a diminishing need for countries to want emigration. Ubicomp's tags for this article

Defects in regulation of apoptosis in caspase-2-deficient mice

Abstract: During embryonic development, a large number of cells die naturally to shape the new organism. Members of the caspase family of proteases are essential intracellular death effectors. Herein, we generated caspase-2-deficient mice to evaluate the requirement for this enzyme in various paradigms of apoptosis. Excess numbers of germ cells were endowed in ovaries of mutant mice and the oocytes were found to be resistant to cell death following exposure to chemotherapeutic drugs. Apoptosis mediated by granzyme B and perforin was defective in caspase-2-deficient B lymphoblasts. In contrast, cell death of motor neurons during development was accelerated in caspase-2-deficient mice. In addition, caspase-2-deficient sympathetic neurons underwent apoptosis more effectively than wild-type neurons when deprived of NGF. Thus, caspase-2 acts both as a positive and negative cell death effector, depending upon cell lineage and stage of development.

Creativity and knowledge: A challenge to theories.

Abstract: An important component of research in creativity has been the development of theories concerning the mechanisms underlying creative thinking. Modern theories of creative thinking have been advanced from many different viewpoints, ranging from Guilford's pioneering psychometric theory (e.g., 1950; see also Runco, 1991) to those developing out of clinical interests, broadly conceived (e.g., Eysenck, 1993). Other theories have developed out of Gestalt psychology (e.g., Wertheimer, 1982), traditional associationistic experimental psychology (e.g., Mednick, 1962), Darwinian theory (e.g., Campbell, 1960; Simonton, 1988, 1995); social-psychological perspectives (e.g., Amabile, 1983), investment perspectives (e.g., Sternberg & Lubart, 1995), and modern cognitive science (e.g., Martindale, 1995). In this chapter, I examine one critical issue confronting all such theories: the role of knowledge in creativity. Although the various theoretical views proposed by psychologists appear on the surface to be very different, there is among many of them, including all those just cited, one critical assumption concerning the relationship between knowledge and creativity. Since creative thinking by definition goes beyond knowledge, there is implicitly or explicitly assumed to be a tension between knowledge and creativity. Knowledge may provide the basic elements, the building blocks out of which are constructed new ideas, but in order for these building blocks to be available, the mortar holding the old ideas together must not be too strong.

The Conservatism Principle and the Asymmetric Timeliness of Earnings

Abstract: Conservatism is interpreted to mean that accountants more frequently report current "bad news" about future cash flows in contemporaneous earnings than current "good news." Thus, earnings reported under GAAP should be more timely in reporting "bad news" about future cash flows than "good news." This paper, using the firm's stock return as a measure of news, shows that the contemporaneous association between earnings and negative returns is two to five times as large as the contemporaneous association between earnings and positive returns. It is also shown that the greater timeliness of earnings relative to cash flow measures is largely due to a greater sensitivity to concurrent negative returns. This result is consistent with accountants recording accruals conservatively. Another implication of conservatism is that negative earnings surprises are likely to be less persistent than positive earnings surprises, because earnings reports more bad news concurrently than good news, with the latter being spread over several periods. This is shown to be true empirically. It is predicted and found that earnings response coefficients are higher for positive earnings changes than for negative earnings changes, which is consistent with the market correcting for the difference in persistence in conservatively determined earnings. It is also found that the sensitivity of earnings to negative returns has more than quadrupled since 1980, while the sensitivity of earnings to negative returns has declined by two-thirds, suggesting that earnings measurement has become more conservative. Increases in accounting conservatism are found to be correlated with increases in auditor liability, but no causal inferences are drawn.

Modulation of life and death by the TNF receptor superfamily.

Abstract: The tumor necrosis factor receptor (TNFR) superfamily represents a growing family, with over 20 members having been identified thus far in mammalian cells. These proteins share significant homologies in their extracellular ligand binding domains and intracellular effector (death) domains. These receptors appear to transmit their signals via protein-protein interactions, which convey either a death or survival signal. Isolation and characterization of death domain containing proteins (TRADD, FADD/MORT-1, RIP), TRAF domain containing proteins (TRAF1-6) as well as new members and adaptor proteins such as DAXX have provided new insights to our understanding of signaling mechanisms associated with this family of receptors. While the death signals seem to be associated with the activation of both the caspase and JUN kinase pathways, the survival signals are mediated via the activation of the NF-κB pathway.

Coactivation of two different G protein-coupled receptors is essential for ADP-induced platelet aggregation

Abstract: ADP is an important platelet agonist causing shape change and aggregation required for physiological hemostasis. We recently demonstrated the existence of two distinct G protein-coupled ADP receptors on platelets, one coupled to phospholipase C, P2Y1, and the other to inhibition of adenylyl cyclase, P2TAC. In this study, using specific antagonists for these two receptors, we demonstrated that concomitant intracellular signaling from both the P2TAC and P2Y1 receptors is essential for ADP-induced platelet aggregation. Inhibition of signaling through either receptor, by specific antagonists, is sufficient to block ADP-induced platelet aggregation. Furthermore, signaling through the P2TAC receptor could be replaced by activation of α2A-adrenergic receptors. On the other hand, activation of serotonin receptors supplements signaling through the P2Y1 receptor. Moreover, this mechanism of ADP-induced platelet aggregation could be mimicked by coactivation of two non-ADP receptors coupled to Gi and Gq, neither of which can cause platelet aggregation by itself. We propose that platelet aggregation results from concomitant signaling from both the Gi and Gq, a mechanism by which G protein-coupled receptors elicit a physiological response.

Results on ν μ → ν e Neutrino Oscillations from the LSND Experiment

Abstract: A search for ${\ensuremath{ u}}_{\ensuremath{\mu}}\ensuremath{\rightarrow}{\ensuremath{ u}}_{e}$ oscillations has been conducted with the LSND apparatus using ${\ensuremath{ u}}_{\ensuremath{\mu}}$ from ${\ensuremath{\pi}}^{+}$ decay in flight. Two analyses observe a total of 40 beam-on high-energy (60--200 MeV) electron events consistent with the ${\ensuremath{ u}}_{e}\mathrm{C}\ensuremath{\rightarrow}{e}^{\ensuremath{-}}X$ inclusive reaction. This number is significantly above the $21.9\ifmmode\pm\else\textpm\fi{}2.1$ events expected from the ${\ensuremath{ u}}_{e}$ contamination in the beam and the beam-off background. If interpreted as an oscillation signal, the observed oscillation probability of $(2.6\ifmmode\pm\else\textpm\fi{}1.0\ifmmode\pm\else\textpm\fi{}0.5)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}$ is consistent with the previously reported ${\overline{\ensuremath{ u}}}_{\ensuremath{\mu}}\ensuremath{\rightarrow}{\overline{\ensuremath{ u}}}_{e}$ oscillation evidence from LSND.

Methodological studies of the Composite International Diagnostic Interview (CIDI) in the US national comorbidity survey (NCS)

Abstract: This paper reports the results of methodological studies carried out in conjunction with the US National Comorbidity Survey (NCS) to evaluate Version 1.0 of the World Health Organization (WHO) Composite International Diagnostic Interview (CIDI). These studies relied on recent survey data collection methodology literature to investigate problems regarding question comprehension, instruction comprehension, respondent motivation to report accurately, and regarding the limits of respondent ability to report accurately. Insights and strategies developed by survey methodologists were used to modify the CIDI in an effort to address these problems. The paper describes these strategies and methodological studies that evaluated their effects, including a clinical reappraisal study and a field experiment that evaluated the impact of question modifications on prevalence estimates. The paper closes with a discussion of remaining methodological problems with the CIDI and potentially useful future studies that might be able to develop solutions to these problems. Copyright © 1998 Whurr Publishers Ltd.

Myocyte Recovery After Mechanical Circulatory Support in Humans With End-Stage Heart Failure

Abstract: Background—The failing myocardium is characterized by decreased force production, slowed relaxation, and depressed responses to β-adrenergic stimulation. In some heart failure patients, heart function is so poor that a left ventricular assist device (LVAD) is inserted as a bridge to transplantation. In the present research, we investigated whether circulatory support with an LVAD influenced the functional properties of myocytes from the failing heart. Methods and Results—Myocytes were isolated from human explanted failing hearts (HF-myocytes) and failing hearts with antecedent LVAD support (HF-LVAD-myocytes). Studies of myocyte function indicated that the magnitude of contraction was greater (9.6±0.7% versus 6.9±0.5% shortening), the time to peak contraction was significantly abbreviated (0.37±0.01 versus 0.75±0.04 seconds), and the time to 50% relaxation was reduced (0.55±0.02 versus 1.45±0.11 seconds) in the HF-LVAD-myocytes compared with the HF-myocytes (P<0.05). The HF-LVAD-myocytes had larger contrac...

Regression of Cellular Hypertrophy After Left Ventricular Assist Device Support

Abstract: Background —Although multiple studies have shown that the left ventricular assist device (LVAD) improves distorted cardiac geometry, the pathological mechanisms of the “reverse remodeling” of the heart are unknown. Our goal was to determine the effects of LVAD support on cardiac myocyte size and shape. Methods and Results —Isolated myocytes were obtained at cardiac transplantation from 30 failing hearts (12 ischemic, 18 nonischemic) without LVAD support, 10 failing hearts that received LVAD support for 75±15 days, and 6 nonfailing hearts. Cardiac myocyte volume, length, width, and thickness were determined by use of previously validated techniques. Isolated myocytes from myopathic hearts exhibited increased volume, length, width, and length-to-thickness ratio compared with normal myocytes ( P <0.05). However, there were no differences in any parameter between myocytes from ischemic and nonischemic cardiomyopathic hearts. Long-term LVAD support resulted in a 28% reduction in myocyte volume, 20% reduction in cell length, 20% reduction in cell width, and 32% reduction in cell length-to-thickness ratio ( P <0.05). In contrast, LVAD support was associated with no change in cell thickness. These cellular changes were associated with reductions in left ventricular dilation and left ventricular mass measured echocardiographically in 6 of 10 LVAD-supported patients. Conclusions —These studies suggest that the regression of cellular hypertrophy is a major contributor to the “reverse remodeling” of the heart after LVAD implantation. The favorable alterations in geometry that occur in parallel fashion at both the organ and cellular levels may contribute to reduced wall stress and improved mechanical performance after LVAD support.

The case for collaborative programming

Abstract: T eam programming usually means coordinating efforts of individual programmers who divide up the programming tasks for a large, complex system. Collaborative programming is used here to mean two programmers working jointly on the same algorithm and code. Previous research indicates that student programmers working collaboratively outperformed individual programmers. A follow-up field experiment was conducted using experienced programmers who worked on a challenging problem important to their organization, in their own environments, and with their own equipment. To the surprise of the managers and participants, all the teams outperformed the individual programmers, enjoyed the problem-solving process more, and had greater confidence in their solutions.

Reversal of Proinflammatory Responses by Ligating the Macrophage Fcγ Receptor Type I

Abstract: Macrophages can respond to a variety of infectious and/or inflammatory stimuli by secreting an array of proinflammatory cytokines, the overproduction of which can result in shock or even death. In this report, we demonstrate that ligation of macrophage Fcγ receptors (FcγR) can lead to a reversal of macrophage proinflammatory responses by inducing an upregulation of interleukin (IL)-10, with a reciprocal inhibition of IL-12 production. IL-10 upregulation was specific to FcγR ligation, since the ligation of the Mac-1 receptor did not alter IL-10 production. The identification of the specific FcγR subtype responsible for IL-10 upregulation was determined in gene knockout mice. Macrophages from mice lacking the FcR γ chain, which is required for assembly and signaling by FcγRI and FcγRIII, failed to upregulate IL-10 in response to immune complexes. However, mice lacking either the FcγRII or the FcγRIII were fully capable of upregulating IL-10 production, implicating FcγRI in this process. The biological consequences of FcγRI ligation were determined in both in vitro and in vivo models of inflammation and sepsis. In all of the models tested, the ligation of FcγR promoted the production of IL-10 and inhibited the secretion of IL-12. This reciprocal alteration in the pattern of macrophage cytokine production illustrates a potentially important role for FcγR-mediated clearance in suppressing macrophage proinflammatory responses.

Role of the retinoblastoma protein family, pRB, p107 and p130 in the negative control of cell growth.

Abstract: The retinoblastoma family of proteins, also known as pocket proteins, includes the product of the retinoblastoma susceptibility gene and the functionally and structurally related proteins p107 and p130. Pocket proteins control growth processes in many cell types, and this has been linked to the ability of pocket proteins to interact with a multitude of cellular proteins that regulate gene expression at various levels. By regulating gene expression, pocket proteins control cell cycle progression, cell cycle entry and exit, cell differentiation and apoptosis. This review will focus on the mechanisms of regulation of pocket proteins and how modulation of pocket protein levels and phosphorylation status regulate association with their cellular targets. The coordinated regulation of pocket proteins provides the cells with a competence mechanism for passage through certain cell growth and differentiation transitions.

An Integrated Approach Toward the Spatial Modeling of Perceived Customer Value

Abstract: The authors present a new measurement methodology of perceived value, based on latent structure multidimensional scaling, that derives simultaneously the underlying dimensions of the perceived value of various brands and market segment heterogeneity in terms of how such value evaluations are made. This latent structure, ordered probit, multidimensional scaling (MDS) based methodology improves on existing industry techniques of illustrating perceived customer value because it enables researchers to infer the underlying dimensions of perceived value from the data without specifying these a priori, as is common in existing methods. The authors compare the proposed model against more traditional MDS approaches in an empirical illustration involving the perceived value of compact cars. Finally, the authors discuss managerial implications of this technique and provide directions for further research.

Signaling by dual specificity kinases

Abstract: Dual specificity kinases that phosphorylate the Thr- and Tyr-residues within the TXY motif of MAP-kinases of play a central role in the regulation of various processes of cell growth. These dual specificity kinases also known as MAP kinase kinases are constituents of the sequential kinase signaling modules. Seven distinct mammalian MAP kinases kinases have been identified. Some of the unique signaling properties of these kinases are discussed here.